Mobile screening apparatus

ABSTRACT

A self-propelled screening apparatus (10) having a support frame (11), endless crawler tracks (15) supporting the frame (11), a hopper (13) and screen or screens (12) mounted on the support frame (11), and a discharge conveyor (14) mounted on the frame (11) and operable to discharge at least one separated portion of screened material (received from the screen) along a required deposition zone while the apparatus is moving.

This invention relates to a mobile screening apparatus of the generaltype which comprises a frame, a screen mounted on said frame, a hopperfor receiving a supply of screenable material and for feeding saidmaterial to the screen so as to be separated-out into screened portionsof different size ranges, means for discharging the separated portionsof screened material from the apparatus, and moving means supportingsaid frame and operable to move the apparatus over the ground.

The invention seeks in particular to provide an improved mobilescreening apparatus of the type referred to above, and which can be usedto carry out screening operations while moving over the ground, and todischarge separated portions of the screened material to requireddeposition zones.

It is of course well known to provide static screening plants, in thesense that all screening operations e.g. in a quarry installation, takeplace while the screening plant is located at a fixed site, although theplant can be transported from one site to another when required. Toachieve easy transportation, it is known to provide a towable screeningplant which has a forward towing hitch, and which has one or morewheelsets to enable the plant to be towed behind a towing vehicle.However, it is mobile only in the sense that it can be towed from onesite to another, after conversion to a transport mode, and actualscreening operations can only take place after the plant has beeninstalled at the new site, and usually after conversion of the plantfrom the transport mode to an operative mode. This generally involvesunfolding discharge conveyors, and any other component parts whichproject outwardly in use.

It is also known to provide travelling hoppers to discharge materialfrom the hoppers onto a prepared site e.g. during laying of hard core toform the base of a motorway carriageway, in which the hopper moves backand forward between a pair of side rails, and also moves progressivelyalong each rail at the end of each path of movement, so that theprepared site becomes filled progressively with hard core.

The invention seeks to provide a mobile screening apparatus which iscapable of (1) receiving a supply of screenable material; (2) screeningthe material e.g. into, at least two different size ranges of screenedmaterial; (3) discharging the separated material; and (4) carrying outall of these operations while the plant is moving, if required, so as todeposit at least one separated portion of screened material in arequired deposition zone.

According to the invention there is provided a mobile screeningapparatus which comprises:

a support frame;

moving means supporting said frame and operable to move the apparatusover the ground;

a screen mounted on said support frame, and a hopper arranged to receivea supply of screenable material and to discharge the material to thescreen so that the latter can separate the material into screenedportions of material; and,

discharge means mounted on the frame and operable to discharge at leastone separated portion of screened material along a required depositionzone while the apparatus is being moved by said moving means.

The invention therefore provides a self-propelled screening apparatus orplant which is capable of receiving a supply of screenable material,separating the material e.g. into at least two size ranges of whichpreferably one includes so-called "fines", and discharging at least oneof the separated range of screened material to a required depositionzone along which the apparatus is moved via said moving means.

Preferably, the discharge means comprises a discharge conveyor arrangedto receive said one separated range of material from the screen, and toconvey the material outwardly of the frame of the apparatus. Theconveyor may be adjustably mounted on the frame, so that the dischargeend of the conveyor can be adjusted laterally and/or upwardly anddownwardly to vary its position relative to the frame.

The conveyor may be mounted to slew about an upright axis which is asubstantially vertical axis when the apparatus is on level ground toadjust itself laterally, and about a substantially horizontal axis tovary the discharge height of the end of the conveyor.

Conveniently, the conveyor is mounted at one end of the frame of theapparatus, and the driver's cab may be mounted at the opposite end, andwith the hopper and screen arranged between them.

The moving means may comprise any suitable form of drivenground-engaging members, but a preferred arrangement comprises a pair ofendless tracks, which is a particularly advantageous way to carry outlateral adjustment of the discharge end of the conveyor.

The apparatus may be used to screen and then distribute screenedmaterial, while on the move, in many different operating environmentse.g. in the laying of hard core on a building site, or the sub-base of aroadway, or in laying "fines" to fill pipeline trenches after thepipelines have been laid.

The screen which is mounted in the apparatus may take any suitabledesign, and may comprise one or more screen deck, and preferably withmeans to apply vibration energy to the screen deck(s) to improve thescreening operation. The screen(s) preferably is arranged to extendgenerally perpendicular to the longitudinal axis of the apparatus (andof the endless track) so that the material which is too large to bescreened i.e. which does not pass through the screens, can be dischargedto one side of the apparatus, and therefore will not obstruct themovement of the apparatus and of its endless tracks.

To provide alternative (or additional) lateral adjustment of theconveyor relative to the endless tracks (and also of the hopper/screensand main superstructure of the apparatus), a slew ring type of mountingplatform may be provided which pivotally mounts the superstructure on abase frame on which the endless tracks are mounted.

A preferred embodiment of mobile screening apparatus according to theinvention will now be described in detail, by way of example only, withreference to the accompanying drawings, in which:

FIG. 1 is a side view of the mobile screening apparatus, and with adischarge conveyor shown unfolded to an operative position;

FIG. 2 is a view from one end of the apparatus;

FIG. 3 is a view, similar to FIG. 1, showing the discharge conveyor in afolded position;

FIG. 4 is a plan view of the apparatus.

FIG. 5 is a view, similar to FIG. 1 and showing a slew ring mounting asa preferred additional component; and

FIG. 6 is a plan view corresponding to FIG. 5.

Referring now to the drawings, there is shown a preferred embodiment ofmobile screening apparatus which is designated generally by reference10, and which is a self-propelled apparatus comprising a support frame11, a screen designated generally by reference 12 mounted on supportframe 11, a hopper 13 for receiving a supply of screenable material andfor feeding such material to the screen 12 so as to be separated outinto screened portions of different size ranges, means for dischargingthe separated portions from the apparatus, and taking the form of adischarge conveyor designated generally by reference 14, and movingmeans in the form of a pair of endless tracks 15 which support the frame11 and are operable to move the apparatus 10 over the ground.

The screen 12 may take any suitable form, and preferably comprises atleast one screen deck, and the entire screen 12 may be mounted on theupper end of frame 11 via suitable flexible linkages 16, and providedwith suitable means to apply vibrational energy to the screen 12 inorder to assist the screening process.

It should be noted that the screen(s) 12 extends generally perpendicularto the longitudinal axis of the apparatus (and of the endless tracks)and therefore oversize material which does not pass through the screenscan be discharged laterally of the endless tracks and therefore will notobstruct the movement of the apparatus.

Screen 12 can separate the screenable material into at least two sizeranges of screened material e.g. to produce so-called "fines" which areseparated from larger material which may be disposed of separately forother uses. The discharge means, in the form of discharge conveyor 14,is mounted at the front end of frame 11 and is operable to discharge atleast one of the separated range of screened material e.g. the "fines"along a required deposition zone while the apparatus 10 is being movedby the endless tracks 15.

The discharge conveyor 14 projects from the frame 11, when in theoperative position shown in FIG. 1, and conveys the screened materialoutwardly of the frame of the apparatus, for discharge to requiredlocations. The conveyor 14 may be arranged to be pivotally adjustablewith respect to the frame 11 about a substantially vertical axis (bysuitable mounting means not shown in detail in FIGS. 1 to 4), so that itcan be slewed to carry out lateral adjustment, and is also capable ofbeing adjusted upwardly and downwardly about a substantially horizontalaxis in order to vary the discharge height of the discharge end of theconveyor 14.

FIG. 3 shows an inwardly folded position of a discharge end portion 14aof the conveyor 14, which it may take-up when the apparatus isinoperative.

The discharge conveyor 14 is mounted at the front end of the frame 11,and the driver's cab 17 may be mounted at the opposite end, and giving afield of view to the driver through the space 18 (see FIG. 2) definedbelow the screen 12, so that the discharge operation for the fines viathe discharge conveyor 14 can be watched. This also assists in theadjustment of the discharge conveyor 14, as well as assisting the driverto follow a required path of movement.

The apparatus 10 may be used to screen and then distribute screenedmaterial, while on the move, in many different environments. By way ofexample, it may be used to lay hard core on a building site, or to formthe base of a roadway. Alternatively, it may be used to lay "fines" tofill pipeline trenches after the pipelines have been laid.

In some circumstances, it may be desirable for the discharge conveyor 14to project from the frame 11 generally in the direction of movement ofthe apparatus, whereas in other situations it may be desirable for it toproject generally perpendicular to the path of movement, so thatscreened material can be deposited to one side of the apparatus.

Although not shown, the apparatus may be arranged so as to be capable ofremote operation e.g. via an umbilical, or a remote control arrangementsuch as an infra red transmitter control device.

Referring now to FIGS. 5 and 6, this shows a slew ring mounting which isa preferred additional component, to provide additional, or alternativemeans for lateral adjustment of the conveyor relative to the endlesstracks (and also of the hopper/screens and the main superstructure ofthe apparatus). The slew ring is shown by reference 21, and thispivotally mounts the main superstructure 19 on a base frame 20 on whichthe endless tracks 15 are mounted.

We claim:
 1. A self-propelled screening apparatus comprising:a supportframe having a longitudinal axis and a pair of opposed sides; a pair ofdriven endless tracks each supporting a respective one of said opposedsides of said frame such that said endless tracks move the apparatusover the ground, each track extending substantially throughout thelength of the respective frame side; a screening device of substantiallythe same length as said endless tracks and overlaying said endlesstracks and fixedly mounted on said support frame, said screening devicehaving a sloping screen extending in a direction between said opposedsides of the support frame and generally perpendicular to saidlongitudinal axis for the support frame; a hopper mounted above thescreening device and arranged to receive a supply of bulk material andto discharge the material to said screen so that the latter can separatethe bulk material into separate portions which comprise non-screenedmaterial which is too large to pass through the screen and screenedmaterial which passes through the screen, in which the screen isarranged to discharge the non-screened material onto the ground adjacentone of the sides of the support frame; and a discharge conveyor mountedon said support frame and projecting therefrom in a direction generallyparallel to the longitudinal axis thereof, said conveyor having adischarge end and a receiving end which is arranged to receive materialwhich has passed through the screen, and said conveyor being operable todischarge such material via the discharge end in a directionlongitudinally of the support frame.
 2. Apparatus according to claim 1,in which the discharge conveyor is adjustable about a transverse axiswhich is substantially horizontal when the apparatus is on level ground,to vary the discharge height of the end of the conveyor.
 3. Apparatusaccording to claim 1, in which the discharge conveyor includes aninnermost portion and an outermost portion hingedly connected together,and adjustable between an operative position in which one of theportions forms a prolongation of the other, and an inoperative foldedposition in which the outermost conveyor portion is inwardly pivoted soas to occupy a space adjacent to said hopper and said screen and therebyto reduce the overall length of the apparatus.
 4. Apparatus according toclaim 1, in which said endless tracks support said frame directly,whereby the lateral position of the discharge end of the conveyor isadjustable by selective operation of the endless tracks.
 5. Apparatusaccording to claim 1, in which the support frame comprises a base framewhich is supported directly by said endless tracks, and a superstructureon which said screen, said hopper and said discharge conveyor aremounted, said superstructure being pivotally mounted on said base frameso as to be capable of slewing the superstructure in order to vary thelateral projection of the discharge end of the conveyor relative to thedirection of forward travel of the apparatus.
 6. Apparatus according toclaim 5, in which said superstructure in mounted on said base frame viaa slew ring.
 7. Apparatus according to claim 1, including a driver's cabmounted at one end of the frame of the apparatus, said dischargeconveyor being mounted at an opposite end, and with the hopper andscreen arranged between the cab and the discharge conveyor.
 8. Apparatusaccording to claim 7, in which a space is defined below the screen andabove the support frame, which provides a field of view from the cab sothat the discharge operation via discharge conveyor can be watched. 9.Apparatus according to claim 1, in which the screen comprises more thatone screen deck.
 10. Apparatus according to claim 1, in which theapparatus includes means operative to render the apparatus capable ofremote operation.
 11. Apparatus according to claim 1, in which theapparatus includes means operative to render the apparatus capable ofbeing remotely operated via an umbilical, or an infra-red transmittercontrol device.
 12. Apparatus according to claim 1, in which thescreening device is configured to screen material while the apparatus ismoved by the endless tracks and while the apparatus is stationary. 13.Apparatus according to claim 1, in which the screening device is capableof screening material while the apparatus is moved by the endlesstracks.
 14. A self-propelled screening apparatus which is capable ofscreening material while it is moving comprising:a support frame havinga longitudinal axis and a pair of opposed sides; a pair of drivenendless tracks each supporting a respective one of said opposed sides ofsaid frame such that said endless tracks move the apparatus over theground, each track extending substantially throughout the length of therespective frame side; a screening device of substantially the samelength as said endless tracks and overlaying said endless tracks andfixedly mounted on said support frame, said screening device having asloping screen extending in a direction between said opposed sides ofthe support frame and generally perpendicular to said longitudinal axisfor the support frame; a hopper mounted above the screening device andarranged to receive a supply of bulk material and to discharge thematerial to said screen so that the latter can separate the bulkmaterial into separate portions which comprise non-screened materialwhich is too large to pass through the screen and screened materialwhich passes through the screen, in which the screen is arranged todischarge the non-screened material onto the ground adjacent one of thesides of the support frame; and a discharge conveyor mounted on saidsupport frame and projecting therefrom in a direction generally parallelto the longitudinal axis thereof, said conveyor having a discharge endand a receiving end which is arranged to receive material which haspassed through the screen, and said conveyor being operable to dischargesuch material via the discharge end in a direction longitudinally of thesupport frame.